The pre-war rangefinder Kodak Retinas are all of the folding type, only three different models were produced.
Having a rangefinder lead to accurate focusing and therefore permitted faster and higher-quality lenses, as generally found on these models.
Kodak Retina II 122
This is the first Retina rangefinder model, which was produced from 1936-1937, and presumably Kodak's answer to the Leica II and II models introduced several years earlier. I believe this was the first rangefinder ever produced by Kodak, although followed soon after by the rangefinder version of the Duo 620 as well as the Super Six-20. In any case, the type 122 was not a great success and only little more than 5000 were produced. However, that does not quite explain its current rarity - the type 150 model was built in equally limited numbers and is much easier to find.
Other than the rangefinder the most remarkable feature of this camera was the presence of a wind lever. I cannot think of any other cameras from that time that had one. However, it must have caused trouble, as the lever was dropped for the next model (the type 142 below) and did not reappear until the Retina Ia and IIa in 1951. Another weakness was the shutter release button: even though it was retractable, it protruded quite far from the top housing and was therefore quite vulnerable.
Nevertheless, this model lay the base for many Retina rangefinders to follow, in fact the focus mechanism and general handling did not change much until the very last folding Retina, the IIIC. Despite its rarity, a few different variants were available, including a choice of lenses: Schneider f/2 or f/2.8 Xenon, or Kodak f/3.5 Ektar (a rebadged Xenar most likely) as well as a top plate with or without a circled II as model indicator. Good luck getting all those!
Front view of a Kodak Retina II 122 with a Retina-Xenon f/2.8 lens. Note this wasn't a true six-element Xenon, but a five-element 'Super-Xenar', so a faster version of the regular four-element f/3.5 Xenar.
I have not seen a manual for this model, so a few notes on the various levers and buttons on this models seems appropriate. On top next to the frame counter is a small button, this is for retracting the shutter release button when not in use. When pushing it in the direction of the arrow, the shutter release button can be pushed down without firing the shutter and will lock into place. Push the locking button again and the shutter release button will pop up, ready for action.
To the side of the camera next to the wind lever is the rewind lever, move it to R to disengage the wind lever to be able to rewind the camera, move it back to A for the wind lever to work. Next to the rewind knob is another small lever, which locks the rewind knob into place, as if it is turned it will block the viewfinder. After rewinding keep turning the knob till it locks into place.
Detail of wind lever and shutter release locking button. Move mouse over picture to see release button retracted.
A final note is on the wind lever itself. The locking nut unscrews the opposite way (clockwise) from normal screws, so turning the 'normal' way will actually tighten it. This probably explains why most examples of this model I have seen have scratched locking nuts, sadly.
By a stroke of good fortune I came into possession of two different Kodak Retina II 122 on the same day. Although I probably have to let one go, I couldn't resist the opportunity to get a shot of the two together. One has a Retina-Xenon f/2.8 lens, the other an Ektar f/3.5. There are a few other small differences (rewind knob mechanism, tripod mount) which shows that even during the short period of production, continuous small improvements were made.
Kodak Retina II 142
This is the second model rangefinder, which was produced from 1937-1939. It is easily recognisable due to the distinct, round viewfinder windows. Note that the 122 had these too, but one does not come across these very often. The viewfinder and rangefinder of the Retina II type 142 had separate eye pieces at the back of the camera.
Other interesting features of the 142 are the large rewind knob and front and top trim of the top housing being screwed on.
Front view of a Kodak Retina II 142 with an uncoated Retina-Xenon f/2 lens, the serial number of which suggest the camera was built around April 1938. This particular one is cosmetically a bit rough. An engraving at the back indicates it was origally sold in Buenos Aires, so it's travelled a long way!
Top view of the same Kodak Retina II type 142. Note that the original shutter release button has been replaced by a simple piston and holes have been drilled for an accessory shoe which is no longer present. The lens also does not focus to infinity, which is rather rare as this is not easy to change, which suggests it has been dis- and reassembled poorly or something is not quite right with the strut mechanism.
A different example of the Kodak Retina type 143, this time with the f/2.8 version of the Retina-Xenon (in actuality a five-element Super-Xenar). Another difference is the 'II' in 'Retina II' engraved on top, on this example it is engraved within a circle. I've noticed this on different Type 122s as well, but I have never been able to figure out why, or when.
Kodak Retina IIa 150
The main difference between the Retina IIa and its predecessor above was that the viewfinder and rangefinder were integrated, so there was only one eye piece at the rear of the camera. This allowed for much more convenient focussing and framing of the shot. Other changes were largely cosmetic, for example the frame counter was moved next to the wind knob and could be adjusted by a small wheel at the front corner of the top housing and the rewind knob was made smaller, so it matched that of contemporary Retina viewfinders. The camera also received an accessory shoe.
Front view of a Kodak Retina IIa type 150 with an uncoated Kodak Ektar f/3.5 lens. This was a rebranded Schneider Xenar lens, the serial number suggests the camera was built around April 1939. Rather unusually, this example had a flash sync socket mounted in the bottom right corner of the shutter.